This page describes the command line for the experimental Java compiler, the Java launcher and HotSpot JVM for the support of L-World Value Types in the Valhalla project.
L-World Value Types flags:
Flag | Description | |
|---|---|---|
| hotspot |
| REQUIRED | -XX:EnableValhalla | Boolean value, default value is `false` If true enable support for L-World value types. |
| -XX:ValueArrayFlatten | Boolean value, default value is `true` Flatten arrays of values, if possible |
| -XX:ValueArrayElemMaxFlatSize | Integer value, default is -1 Max size for flattening an array of values, < 0 means no limit |
| -XX:ValueArrayElemMaxFlatOops | Integer value, default is 4 Max number of embedded object references in value type to flatten in an array, < 0 means no limit |
| -XX:BigValueTypeThreshold | size_t value in bytes, default is 4 * BytesPerLong Max value type size for interpreter buffering of local variable table entries |
| -XX:ValueArrayAtomicAccess | Boolean value, default value is `false` Enable atomic access to values in an array, by treating value types as references. |
| -XX:+PrintEliminateAllocations | Non-product builds: Print out when allocations are eliminated |
| -XX:+PrintEscapeAnalysis | Non-product builds: Print results of escape analysis (e.g. if you believe boxing was not eliminated) | |
| java |
| javac |
| -XDallowGenericsOverValues | Allow generic parameters/bounds/witnesses. Default false |
| -XDallowFlattenabilityModifiers | Allow source level field flattenability modifiers __Flattenable, _NotFlattened |
| -XDallowValueBasedClasses | Leniency mode for value-based-class migration |
| -XDallowEmptyValues | allow value classes with no instance fields (hotspot will currently disallow) |
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